1. Field of the Invention
The present invention relates to the recovery of catalyst components from process residue and more particularly, to a process for recovery of triarylboranes and metals from the process residue obtained from the hydrocyanation of olefins, e.g., from the preparation of adiponitrile by hydrocyanation of butadiene using nickel or palladium complexes as catalysts with triphenylborane as the catalyst promoter.
2. Description of the Prior Art
A general disclosure of typical processes to which the present invention can be applied is found in the publication entitled "Hexamethylene Diamine" in The Process Economics Program Report No. 31-A, Stanford Research Institute, Menlo Park, C.A.; September, 1972. More particularly, the hydrocyanation process to which the present invention can be applied is disclosed in U.S. Pat. Nos. 3,496,215 issued on Feb. 17, 1970, 3,496,218 issued on Feb. 17, 1970, 3,542,847 issued on Nov. 24, 1970, and 3,752,839 issued on Aug. 14, 1973. The residue from the above-disclosed process is obtained by removing the substantial portion of desired products, unreacted materials and intermediates from the reactor effluent, separating solvent and other volatiles from the resultant stream for recycle to the reactor and thereafter obtaining a concentrated waste stream.
The solids in this concentrated waste stream are principally catalyst residues which represent a significant economic penalty if not recovered. The present invention is directed to the recovery of the catalyst and catalyst promoter in the waste stream.
Some chemistry has been disclosed for the reactions involving the ammonia adduct of triarylborane. Ammonia displacement from this adduct by reacting the adduct with quaternary ammonium fluoride and hydroxide salts in the presence of ethanol to produce complex salts is disclosed by D. L. Fowler and C. A. Kraus, J. Am Chem. Soc., 62, 1143 (1940). This adduct was reacted with dry hydrochloric acid in the presence of ether by Mikhailov et al. [Izvest. Akad. Nauk S.S.S.R., Otdel. Kimm. Nauk, 812 (1957)] to produce triphenylborane and ammonium chloride. G. Wittig et al. [Ann. Chem., 573, 195 (1951)] produced triphenylborane by thermally decomposing (CH.sub.3).sub.3 NH+B(C.sub.6 H.sub.5).sub.4 -- and further disclose the preparation of the sodium hydroxide salt of triphenylborane by fusion of the borane with sodium hydroxide and the reaction of the salt with ammonium chloride or hydroxide to yield .phi..sub.3 --B.NH.sub.3. The borane was also reacted with sodium cyanide to yield a compound postulated to have the formula [.phi..sub.3 (CN)B]Na.